The ear canal is generally narrow and tortuous and is approximately 26 millimeters (mm) long from the canal aperture 11 to the tympanic membrane 15 (eardrum). The lateral part 12 is referred to as the cartilaginous region due to the underlying cartilaginous tissue 16 beneath the skin. The medial part, proximal to the tympanic membrane 15, is rigid and referred to as the bony region 13 due to the underlying bone tissue 17. A characteristic first bend occurs roughly at the aperture 11 of the ear canal. A second characteristic bend occurs roughly at the bony-cartilaginous junction 8 and separates the cartilaginous region 12 and the bony region 13. The ear canal 14 is generally hidden from view (front and side) behind a backward projecting eminence known as the tragus. The ear canal is also hidden from view from the back by the presence of the pinna (also referred to as auricle). The dimensions and contours of the ear canal 14 vary significantly among individuals.
Placement of a hearing device inside the ear canal 14 is generally desirable for various electroacoustic advantages such as reduction of the acoustic occlusion effect, improved energy efficiency, reduced distortion, reduced speaker vibrations, and improved high frequency response. Canal placement may also be desirable for cosmetic reasons since the majority of the hearing impaired may prefer to wear an inconspicuous hearing device. A canal hearing device can be inserted entirely or partially inside the ear canal. In the context of this application, any hearing device inserted inside the ear canal, whether partially or completely, may be referred to as a canal hearing device. This includes what is known in the hearing aid industry as Completely In the Canal (CIC), Receiver-In-Canal, (RIC), In-The-Canal (ITC), and extended wear deep canal invisible types.
Hearing devices may include a battery, which may be disposable or rechargeable. With either disposable or rechargeable batteries, removal (e.g., for charging) or replacement of the battery may be difficult or cumbersome for some users, particularly those with impaired dexterity, due to a relatively small form factor of hearing devices. In addition, the entry cost for a hearing device may be substantially high making it cost prohibitive for a large number of potential users to purchase a hearing device. Improvements in the field of hearing devices and systems may be desirable.